首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   215553篇
  免费   17705篇
  国内免费   7980篇
耳鼻咽喉   2006篇
儿科学   2743篇
妇产科学   2522篇
基础医学   32164篇
口腔科学   3472篇
临床医学   15850篇
内科学   37122篇
皮肤病学   2862篇
神经病学   14971篇
特种医学   5590篇
外国民族医学   73篇
外科学   16346篇
综合类   29366篇
现状与发展   20篇
一般理论   6篇
预防医学   10159篇
眼科学   2034篇
药学   32611篇
  44篇
中国医学   8217篇
肿瘤学   23060篇
  2024年   536篇
  2023年   3956篇
  2022年   8591篇
  2021年   10530篇
  2020年   8045篇
  2019年   6886篇
  2018年   6618篇
  2017年   6613篇
  2016年   6878篇
  2015年   8028篇
  2014年   12454篇
  2013年   13542篇
  2012年   12177篇
  2011年   14137篇
  2010年   11775篇
  2009年   12144篇
  2008年   11885篇
  2007年   11062篇
  2006年   9946篇
  2005年   8701篇
  2004年   7332篇
  2003年   6542篇
  2002年   5295篇
  2001年   4441篇
  2000年   3695篇
  1999年   3237篇
  1998年   3012篇
  1997年   2767篇
  1996年   2408篇
  1995年   2118篇
  1994年   1925篇
  1993年   1632篇
  1992年   1376篇
  1991年   1289篇
  1990年   1051篇
  1989年   866篇
  1988年   832篇
  1987年   700篇
  1986年   639篇
  1985年   983篇
  1984年   923篇
  1983年   647篇
  1982年   663篇
  1981年   524篇
  1980年   443篇
  1979年   368篇
  1978年   240篇
  1977年   202篇
  1976年   185篇
  1975年   127篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
目的对附加钢板技术治疗股骨干髓内钉术后骨不连的历史、现状和进展进行综述。方法广泛查阅国内外关于附加钢板技术治疗股骨干髓内钉术后骨不连的临床研究文献,并进行综合分析。结果自 1997 年附加钢板技术已成功用于治疗股骨干髓内钉术后骨不连,根据原髓内钉是否失效,可分为保留原髓内钉和更换原髓内钉两类。该技术不仅适用于简单骨不连,还可用于合并严重畸形的复杂性骨不连。相比更换髓内钉、更换外侧钢板和双钢板技术,附加钢板技术手术创伤更小,骨折愈合时间更短,骨折愈合率更高,患者能更早重返社会和工作。然而,该技术也存在一些问题有待解决,包括双皮质螺钉固定困难、缺乏适合股骨干解剖型附加钢板以及缺乏术后功能和生活质量的评估研究。结论相比其他翻修固定方式,附加钢板技术能够获得更高的骨折愈合率和更好的临床预后。然而,术后患者能否在功能和生活质量方面进一步获益还有待证实。此外,还需要更高质量的临床对照研究深入证明其是否确实优于其他翻修固定方式。  相似文献   
122.
123.
BackgroundNew antidiabetic agents (sodium-glucose cotransporter-2 inhibitor [SGLT2i] and glucagon-like peptide-1 receptor agonist [GLP-1RA]) and metabolic surgery have protective effects on metabolic syndromes.ObjectivesTo compare the changes of metabolic parameters and costs among patients with obesity and type 2 diabetes undergoing metabolic surgery and initiating new antidiabetic agents over 12 months.SettingHong Kong Hospital Authority database from 2006–2017.MethodsThis is a population-wide retrospective cohort study consisting of 2616 patients (1810 SGLT2i, 528 GLP-1RA, 278 metabolic surgery). Inverse probability treatment weighting of propensity score was applied to balance baseline covariates of patients with obesity and type 2 diabetes who underwent metabolic surgery, or initiated SGLT2i or GLP-1RA. Metabolic parameters and direct medical costs were measured and compared from baseline to 12 months in metabolic surgery, SGLT2i, and GLP-1RA groups.ResultsPatients in all 3 groups had improved metabolic parameters over a 12-month period. Patients with metabolic surgery achieved significantly better outcomes in BMI (?5.39, ?.56, ?.40 kg/m2, P < .001), % total weight loss (15.16%, 1.34%, 1.63%, P < .001), systolic (?2.21, ?.59, 1.28 mm Hg, P < .001) and diastolic (?1.16, .50, ?.13 mm Hg, P < .001) blood pressure, HbA1c (?1.80%, ?.77%, ?.80%, P < .001), triglycerides (?.64, ?.11, ?.09 mmol/L, P < .001), and estimated glomerular filtration rate (3.08, ?1.37, ?.41 mL/min/1.73m2, P < .001) after 12 months compared with patients with SGLT2i and GLP1-RA. Although the metabolic surgery group incurred the greatest direct medical costs (US$33,551, US$10,945, US$10,627, P < .001), largely due to the surgery itself and related hospitalization, the total monthly direct medical expenditure of metabolic surgery group became lower than that of SGLT2i and GLP-1RA groups at 7 months.ConclusionBeneficial weight loss and metabolic outcomes at 12 months were observed in all 3 groups, among which the metabolic surgery group showed the most remarkable effects but incurred the greatest medical costs. However, studies with a longer follow-up period are warranted to show long-term outcomes.  相似文献   
124.
125.
The current coronavirus disease (COVID‐19) outbreak, caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), has raised the possibility of potential neurotropic properties of this virus. Indeed, neurological sequelae of SARS‐CoV‐2 infection have already been reported and highlight the relevance of considering the neurological impact of coronavirus (CoV) from a translational perspective. Animal models of SARS and Middle East respiratory syndrome, caused by structurally similar CoVs during the 2002 and 2012 epidemics, have provided valuable data on nervous system involvement by CoVs and the potential for central nervous system spread of SARS‐CoV‐2. One key finding that may unify these pathogens is that all require angiotensin‐converting enzyme 2 as a cell entry receptor. The CoV spike glycoprotein, by which SARS‐CoV‐2 binds to cell membranes, binds angiotensin‐converting enzyme 2 with a higher affinity compared with SARS‐CoV. The expression of this receptor in neurons and endothelial cells hints that SARS‐CoV‐2 may have higher neuroinvasive potential compared with previous CoVs. However, it remains to be determined how such invasiveness might contribute to respiratory failure or cause direct neurological damage. Both direct and indirect mechanisms may be of relevance. Clinical heterogeneity potentially driven by differential host immune‐mediated responses will require extensive investigation. Development of disease models to anticipate emerging neurological complications and to explore mechanisms of direct or immune‐mediated pathogenicity in the short and medium term is therefore of great importance. In this brief review, we describe the current knowledge from models of previous CoV infections and discuss their potential relevance to COVID‐19.  相似文献   
126.
《Value in health》2020,23(10):1340-1348
ObjectivesWe applied principles for conducting economic evaluations of factorial trials to a trial-based economic evaluation of a cluster-randomized 2 × 2 × 2 factorial trial. We assessed the cost-effectiveness of atorvastatin, omega-3 fish oil, and an action-planning leaflet, alone and in combination, from a UK National Health Service perspective.MethodsThe Atorvastatin in Factorial With Omega EE90 Risk Reduction in Diabetes (AFORRD) Trial randomized 800 patients with type 2 diabetes to atorvastatin, omega-3, or their respective placebos and randomized general practices to receive a leaflet-based action-planning intervention designed to improve compliance or standard care. The trial was conducted at 59 UK general practices. Sixteen-week outcomes for each trial participant were extrapolated for 70 years using the United Kingdom Prospective Diabetes Study Outcomes Model v2.01. We analyzed the trial as a 2 × 2 factorial trial (ignoring interactions between action-planning leaflet and medication), as a 2 × 2 × 2 factorial trial (considering all interactions), and ignoring all interactions.ResultsWe observed several qualitative interactions for costs and quality-adjusted life-years (QALYs) that changed treatment rankings. However, different approaches to analyzing the factorial design did not change the conclusions. There was a ≥99% chance that atorvastatin is cost-effective and omega-3 is not, at a £20 000/QALY threshold.ConclusionsAtorvastatin monotherapy was the most cost-effective combination of the 3 trial interventions at a £20 000/QALY threshold. Omega-3 fish oil was not cost-effective, while there was insufficient evidence to draw firm conclusions about action planning. Recently-developed methods for analyzing factorial trials and combining parameter and sampling uncertainty were extended to estimate cost-effectiveness acceptability curves within a 2x2x2 factorial design with model-based extrapolation.  相似文献   
127.
The aetiology of vitiligo has not been fully elucidated, and several hypotheses have been investigated; among them, the most explored assumes an autoimmune basis for the disease. Supporting this hypothesis is the frequent co-occurrence of autoimmune diseases with vitiligo. In addition, various genetic loci associated with vitiligo harbour key immune response genes. Our general hypothesis is that autoimmunity-associated genes participate in the control of vitiligo susceptibility. To investigate this hypothesis, we tested for association between vitiligo and genes CYP27B1, REL, TNFAIP3 and IL2/IL21, all previously related to autoimmune diseases associated with vitiligo. The study was performed using two independent population samples: a family-based discovery set (211 trios) and a replication set (131 cases/119 controls). Statistically significant association with vitiligo was detected between markers of the REL and IL2 gene in the family-based sample. Both association signals were concentrated among patients displaying autoimmune comorbidity and non-segmental vitiligo. Evidence for validation was detected for IL2 marker. Our findings suggest REL and IL2 as new vitiligo susceptibility genes and reinforce the hypothesis of a shared genetic mechanism controlling vitiligo and other autoimmune diseases.  相似文献   
128.
目的探讨先天性中枢性低通气综合征(CCHS)的临床和基因变异特征。方法分析1例首发表现为不明原因肺动脉高压的CCHS患儿的临床资料,并总结国内外文献中CCHS病例的临床特点、致病机制和基因变异情况。结果11月龄女婴,主要表现为浮肿、尿少、低血压、嗜睡、发绀、抽搐及颅内压增高。B型脑利钠肽、丙氨酸氨基转移酶升高,凝血酶原时间延长。颅脑磁共振示右侧额叶出血;超声心动图示中重度肺动脉高压。靶向捕获二代测序未发现可能的致病基因。采用Sanger法验证示患儿PHOX 2 B基因第3外显子存在多聚丙氨酸重复扩展变异,基因型为20/25。患儿入院后采用无创通气,睡眠时呼吸浅慢、微弱,伴血氧下降;血气分析提示二氧化碳潴留。随后改用夜间无创通气、降肺压药物治疗。复查肺动脉压力明显下降,生命体征稳定。随访至24月龄,夜间只需较低压力水平的无创通气,生长发育无异常。结论对于不明原因的肺动脉高压伴撤机困难患儿,需警惕CCHS。疑诊者应尽早针对CCHS相关基因进行靶向捕获二代测序及PHOX 2 B基因Sanger法验证。早期给予无创通气有望改善预后。  相似文献   
129.
130.
OBJECTIVES: To assess the effectiveness and safety of additional bedtime H2‐receptor antagonists (H2RAs) in suppressing nocturnal gastric acid breakthrough (NAB) via a systematic review. METHODS: Eligible trials were identified by searching the Cochrane Central Register of Controlled Trials (CENTRAL) (Cochrane Library Issue 2, 2004), MEDLINE (January 1966–June 2004), EMBASE (January 1980–June 2004) and CINAHL (January 1982–June 2004). Additional hand‐searching was conducted on the proceedings of correlated conferences, eight important Chinese journals and references of all included trials. All randomized controlled trials evaluating H2RAs for the control of NAB were eligible for inclusion. The systematic review was conducted using methods recommended by The Cochrane Collaboration. RESULTS: Only two randomized crossover studies, comprising 32 participants, met the inclusion criteria. Because the design, dosage and duration of the treatments were different between the studies, it was not possible to conduct meta‐analysis. There were no consistent conclusions found between the two included studies in evaluating H2RAs for the control of NAB. CONCLUSIONS: No implications for practice at this stage can be concluded. Appropriately designed large‐scale randomized controlled trials with long‐term follow up are needed to determine the effects of additional bedtime H2RAs in suppressing NAB.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号